The present invention relates to a new and improved method and apparatus for the fabrication of molded articles or bodies formed of fiber reinforced material and also pertains to improved molded articles formed in accordance with the aforesaid method and through the use of the aforesaid apparatus constructions of this development. In its more specific aspects the present invention relates to new and improved molded articles formed of a first polymeric material containing embedded fibers which are essentially oriented and a second material having a modulus of elasticity which deviates from that of the aforesaid first material, the articles produced by this invention being, by way of example, tires, conveyor bands, wound-or heating bellows, and further, this invention pertains to a novel method and apparatus for the production of these molded articles.
It is known to form molded articles from elastomeric materials by injection molding or extrusion in molds. In this respect it is also here mentioned that reinforcement inserts can be placed into the mold prior to the injection molding or extrusion operations. In order to overcome the need for such additional operational procedures it has already been proposed to introduce into the mixture these reinforcement elements, for instance in the form of short glass fibers, textile or metallic yarns, and then to inject into the mold the mixture containing these fibers, yarns or the like. When using this procedure it is also of course possible to fabricate strand-like or continuously molded articles. Since in both cases a flow operation occurs in which individual parts of the material carry out a relative movement with respect to one another the yarns or fibers are placed in essentially parallel orientation relative to one another with regard to the flow direction, in other words they are oriented. Hence there is obtained a molded article, which owing to the oriented fibers, is improved in respect of its strength characteristics in the direction of fiber orientation whereas it possesses a lower strength in a direction perpendicular to such fiber orientation direction. These strength differences which are desired for a great many molded articles are the same throughout all portions or sections of the body or article. In a great number of cases, however, it is also desired for certain reasons to have different strength characteristics prevail at different sections of the molded article.